A circuit arrangement is disclosed in the offprint from ZEV-DET Glasers Annalen, Issue 2/3 1994: Rudolf Wagner “Drehstrom-Antriebstechnik für Diesellokomotiven in Nordamerika” [Three-phase drive technology for diesel locomotives in North America]. The three-phase drive technology described therein requires the use of a voltage link converter between the voltage supply and the three-phase motor. During braking, the traction motors become generators, such that current is fed back to the voltage link converter. In this case, it would be possible for GTO thyristors provided in the converter to be damaged by overcurrents and overvoltages.
It is known from the work mentioned, to use a hardware protection system for the purpose of preventing such damage. In the same work it is also proposed to use a simple short-circuit thyristor for the purpose of reducing an overvoltage, since this does not require much space and is also more cost-effective than a protection system.
The protection systems described can only be used if the converter has GTO thyristors, since in this case the current-carrying capacity is high.